Getting from $100 to $500
$10/week became normal? Make it $20. You built the pipe; now widen it.
Clothes, electronics, furniture: a focused Saturday of listings commonly adds $100-$300.
Rebates, refunds, birthday cash, the third paycheck in a 3-paycheck month — by pre-decided rule, half goes in.
Bills and groceries only. Typical harvest: $30-$80, plus a surprisingly useful list of things you didn't miss.

What $500 changes
The $340 brake job no longer becomes a 400% APR loan or a missed electric bill.
Cash cushions EARN a little; emergency borrowing COSTS a lot. $500 is where the sign changes.
People who reach $500 overwhelmingly keep going — the machinery already exists.